Presser mechanism for sewing machines



' July 14, 1942. N. v CHRISTENSEN 2,289,902 PRESSER MECHANISM FOR SEWINGMACHI NES Filed March 12, 1940 3 Sheets-Sheet 1 sZe INVEZNTOR: Mzrman)[Chn BY WW ATTORNEYS.

WITNESSES: "Zr Mai July 14, 1942, N. v. CHRISTENSEN ,2

PRESSER MECHA NIM FOR SEWING MACHINES y 1942- N. v. CHRISTENSEN21,289,902

PRESSER MECHANISM FOR SEWING MACHINES s Sheets-Shet 3 Filed Ma rch 12,1940 ill Illll WITNESSES} INVENTOR: 2 1 iyfirman lf'hristensen,

A TTORNEYS.

Patented July 14, 1942 UNiTE.

PRESSER MECHANISM FOR SEWING MACHINES Norman V. Christensen, Chicago,Ill., assignor to Union Special Machine Company, Chicago, Ill.,

a corporation of Illinois Application March. 12, w ll), Serial No.323,519 8 Claims. (01. 112-235) This invention relates to pressermechanism useful in connection with sewing machines to hold down thework as it is advanced and stitched in the machines.

In the usual types of presser mechanisms, the presser bar extends upinto the needle head and is acted upon either by a helical spring withinthe head, or by a leaf spring, which, in most instances is mounted onthe top of the needle arm and bears on the upper protruding end of saidbar. Such usual construction ordinarily entails careful machining of theneedle head and bushing of the points where the opposite ends of thepresser bar protrude, and moreover, involves the use of relatively heavyparts which are sluggish in their action and which accordingly limit theoperative speed of the machines.

One of the aims of my invention is to overcome the above drawbacks. lhisobjective I realize in practice, as hereinafter more fully disclosed, ina presser unit which is small, light and compact, and which is designedfor attachment to a pendant projection on the needle head, beingtherefore conveniently accessible at the exterior of the machine framefor the purposes of ready adjustment or replacement.

In connection with a presser unit having the foregoing attributes, it isa further aim of my invention to provide for control of the presser unitfor the purpose of facilitating initial insertion of the work and itssubsequent withdrawal from beneath the presser foot. This desideratum Irealize in practice, as also hereinafter more fully disclosed, in asimple means of which most of the parts, except for the protruding endof an actuating lever at the back of the needle arm, are enclosed andprotected within the machine frame.

Other objects and advantages will appear from the following detaileddescription of the attached drawings wherein Fig. I is a view in topplan of a sewing machine conveniently embodying the presser mechanism ofmy invention, portions of the machine frame being broken out to exposeimportant parts which would otherwis be hidden.

Fig. II is a view of the machine, partly in front elevation and partlyin longitudinal section taken as indicated by the angled arrows II-II inFig. I.

Fig. III shows the end view of the needle head of the machine with itscover plate removed.

Fig. IV is a fragmentary view, partly in side elevation, and partly inlongitudinal section taken axially through the free end of the worksupporting arm.

Fig. V is a cross sectional view of the needle arm taken as indicated bythe arrows VV in Fig. I; and

Fig. VI is a fragmentary detail view corresponding to Fig. II showing analternative detail feature of my invention.

The sewing machine herein illustrated for convenience of exemplifying myinvention is of the feed off the arm type of the construction disclosedin a copending patent application Serial No. 306,826, filed by me onNovember 30, 1939. As shown, the machine has a base i from which extendshorizontally, a work supporting arm 2 of right angle configuration, andfrom which rises a standard 3 sustaining a needle arm 3 with a needlehead 5 at its free end directly over the free end of said work arm.Partitions 5 and 1 within the needle arm 4 set apart a central chamber 8between the hollow of the standard 3 and the hollow of the needle head5; and fitted into said partitions are bearing bushings 9 and Ill for ahorizontal shaft ll. As shown, this shaft H extends to the exteriorthrough another bearing bushing l2 in the back side wall of the standard3 and on its protruding end is provided with a combined hand and beltwheel it; whereby the machine may be manually or power driven. At itsleft hand end within the head 5, the shaft ll carries a counter balancedcrank member l5, which, through a pitman it, imparts endwisereciprocating movements to a vertical needle bar i1 having guidance ininset bushings l8 and i9 at the top and bottom of the needle head 5.Secured in the lower end of the needle bar H is a group of needles 25](Fig. IV) which cooperate with corresponding loopers 2! on the left handend of a horizontal shaft 22 within the hollow of the work arm 2. Bysuitable concealed mechanism within the work arm 2, the shaft 22 isreciprocated endwise and also oscillated for impartation of needleavoiding and loop taking movements to the loopers 2i incident to theformation of chain stitching in a well known way. Also within the workarm 2 is a feed bar 25 which carries a feed dog 26 whereof the toothedportions protrude through longitudinal slots in a throat plate shown at21 to advance the work forwardly along said arm while it is beingstitched. The necessary endwise and lift movements are induced in thefeed bar 25 by the aforementioned concealed mechanism within the workarm, said mechanism being in turn operated through suitable concealedconnections which includes a train of spur gears 28 (Figs. I and II),from the drive (needle) shaft II. From Fig. II, it will be noted that aspoon 29 on the pitman I dips intermittently into a supply of oil in asump 30 at the bottom of the needle head to splash about the oil so asto automatically lubricate the needle actuating mechanism.

The presser mechanism which constitutes the subject of my presentinvention includes a presser foot 3| which is pivotally connected to ashank member 32 at the bottom end of a short vertical presser bar 33,see Figs. II and IV. As shown, this presser bar 33 is supported withcapacity for endwise up and down movement in a bracket 34 secured by apair of set screws 35 to a projection in the form of a rod 36 pendantfrom the needle head 5. As shown in Fig. III, the upper end of the rod36 is anchored in the bottom of the needle head 5 and secured inadjusted position by a set screw 31. At its lower end, the rod 36 isprovided with a diametrical slot 39 (Fig. II) in which a lateralprojection 40 of the shank member 32 is engaged to prevent rotation ofthe presser bar 33. Bearing on the top of the presser bar 33 is the freeend of a small horizontal leaf spring 4| whereof the other end isanchored at 42 in the outer end of a lateral arm projection 43 of thebracket 34. The pressure of the spring 4| is regulatable by means of acap screw 45 whereof the shank is threaded into a tapped boss 41 on thearm 43 of the bracket 34. The above described presser unit arrangementis advantageous in that it is small and compact, and in that all of itsparts are external to the needle head 5 where they are convenientlyaccessible for the purposes of adjustment or replacement. Since thecomponent parts of the presser unit are small and light, it follows thatthey will respond quickly to irregularities in the thickness of the workbeing seamed as it is progressed on the work arm 2 by the feed dog 26and thus function properly during high speed operation of the machine.

In order that the presser foot 3| may be controlled by means of a kneepress or foot treadle (not illustrated) so that the hands of theoperator may be left free to manipulate the work during the seaming, Ihave made further provisions as follows: Disposed within the rear of theneedle arm 4 at a level above the shaft II in parallel relation thereto,is a rock shaft with its ends journalled in the partitions 6 and I. FromFigs, II anad III it will be observed that the rock shaft 50 extendsinto the needle head 5 where it carries a horizontal crank arm 5|, whichthrough a flexible connector in the form of a, cable 52, is connected toa screw stud 53 projecting laterally from the presser bar 33, see Fig,IV. As shown in Fig. III, the flexible connector 52 passes through avertical tube 55 fitted into the bottom of the needle head 5, the heightof said tube being such as to insure against escape of oil from withinsaid head. As an alternative, a plunger piece 56 may be interposed, seeFig. VI, in the flexible connector 52, said plunger piece having asliding fit in the tube 55 to preclude oil leakage from the needle head5. The rock shaft 50 is operable by means of a lever 51 which extendslaterally outward from the shaft 50 through a clearance opening 58 inthe back side wall of the needle arm 4, see Figs. I and III, and whichis provided with an eye 59 at its outer end for connection by a chain orlink with the knee press or foot treadle hereinbefore referred to. Asshown in Fig. II, the lever 5'! has a hub or sleeve 60 of considerablelength, which at one end abuts the partition 1, and which, incooperation with a collar 6| on the shaft 50 abutting the partition 6,holds said shaft against endwise displacement. A helical torsion springshown at 62 (Figs. I anad III) with one end restrained by the rear sidewall of the needle head 5 and with its other end hooked over the crankarm 5|, serves to normally maintain the lever 51 in the positionillustrated with its top edge bearing against the top of the clearanceopening 58 in the needle arm 4 and with the flexible cable 52 slacked sothat it does not interfere with the normal action of the presser foot3|.

The chamber 8 of the needle arm 4 is utilized as a protective housingfor the devices 63 (Figs. I, II and V) by which the needle threadsrespectively designated by the letter T are maintained under tensionduring the sewing. Each of the devices comprises a pair of opposingdisks 64 and 65 between which the thread T passes, said disks beingsubject to the pressure of a regulatable spring 66 and supported on ahorizontal plate 61 at the top of a cross web 68 within the needle arm4; The control stems 69 of the tension devices 63 pass down through theplate 61 into the path of a wing 10 on the hub 60 of the lever 51 andduring the lifting of the presser foot 3| by rocking of the shaft 50,they are concurrently lifted to relieve the tension on the needlethreads. Since the tension devices 63, per se, are of well knownconstruction further description of them is deemed unnecessary here. Enroute from suitable individual sources of supply, the needle threads Tenter the chamber 8 through eyes H at the back of the needle arm 4 andafter having traversed the tensions 53 emerge through eyes 12 at thefront of the needle arm. From thence, the threads T pass through a guide14 and over a guide hook 15 at the side of the needle head 5 to theneedles 20. In the interval between the guide 14 and the hook 15, theneedle threads T are acted upon by a take up 16 connected to the needlebar II. All the parts within the chamber 8 are readily accessible uponretraction of a cover 11 which closes an access opening in the top ofthe needle arm 4.

Although I have shown and described the presser mechanism of myinvention as embodied in a feed off the arm sewing machine, it isobvious that it may be used in other types of sewing machines withoutsacrifice of any of the advantages which have been pointed out.

Having thus described my invention, I claim:

1. In a sewing machine having a frame with a work support and anoverhanging needle arm, presser mechanism including a bracket securedwith capacity for up and down adjustment to a rigid projection pendantfrom the outer end of the needle arm; a presser bar guided for up anddown movement in the bracket with its upper and lower ends protrudingabove and below the bracket, a presser foot attached to the lower end ofthe bar; and a regulatable spring bearing upon the upper end of thepresser bar to yieldingly urge the presser foot toward the work support.

2. Presser mechanism according to claim 1, wherein the bracket has alaterally extending arm; wherein the spring is in the form of a tongueanchored in the outer end of the bracket arm with its free end bearingon the top of the presser bar; and wherein a cap screw for adjusting thepressure of the spring has its shank passing down through said springand threadedly engaging into the bracket.

3. The combination according to claim 1, wherein the needle arm ishollow; wherein the presser mechanism further includes a horizontal rockshaft journaled within the needle arm; a lifting connection extending upfrom the presser bar and into the outer end of the needle arm to therock shaft; and means whereby the rock shaft may be actuated from theexterior of the machine frame.

4. The combination according to claim 1, wherein the needle arm ishollow; wherein the presser mechanism further includes a horizontal rockshaft journaled within the needle arm, a flexible lifting cableextending up from the presser bar and through the needle arm to alifting arm on the rock shaft, and means whereby the rock shaft may beactuated from the ex terior of the machine frame.

5. The combination according to claim 1, wherein the needle arm ishollow and has an oil sump at the bottom of its outer end; wherein theouter end of the arm contains needle actuating mechanism lubricated withoil taken from the sump; and wherein the presser mechanism furtherincludes a horizontal rock shaft journaled within the needle arm, aflexible cable lifting connection extending up from the presser bar toan arm on the rock shaft, a plunger piece interposed in the cable, and abushing set into the bottom wall of the needle arm in which the plungerpiece has a sliding fit.

6. In a sewing machine having a base with a work support, a hollowoverhanging arm terminating in a needle head above the free end of thework support, and a needle bar guided for up and down movement in theneedle head; needle bar actuating mechanism within the head lubricatedby splash action from an oil sump at the bottom of the head; pressermechanism comprising a presser element guided for up and down movementexteriorly of the head, and means whereby the presser element may belifted when necessary in introducing the work beneath it including arock shaft which extends longitudinal- 1y of the arm aforesaid and intothe needle head, a lever arm on the shaft within the head, a connectionextending from said lever arm down through a tube within the head to thepresser element, the top of said tube being above the oil level and outof the range of the oil splash, and an operating lever on the rock shaftwithin the compartment extending outward through a clearance opening inthe wall of said overhanging arm.

7. In a sewing machine having a base with a work support, a hollowoverhanging arm terminating in a needle head above the free end of thework support; a needle bar guided for up and down movement in the needlehead; a shaft within the arm; needle bar actuating mechanism within thehead driven from the shaft and lubricated by splash action from an oilsump at the bottom of the head, a partition separating the hollow of thehead from an adjacent oil tight compartment within the overhanging arm,and a needle thread tension within the compartment; presser mechanismcomprising a presser element guided for up and down movement exteriorlyof the head, means whereby the presser element may be lifted whennecessary in introducing the work beneath it including a rock shaftwhich extends longitudinally of the compartment aforesaid and into theneedle head, a lever arm on the shaft within the head, a connectionextending from said lever arm down through a tube within the head to thepresser element, the top of said tube being above the oil level and outof the range of the oil splash, an operating lever on the rock shaftwithin the compartment extending outward through a clearance opening inthe wall of said overhanging arm, and means also on the rock shaft forcontrolling said thread tension concurrently with lifting of the presserelement.

8. The combination according to claim 1 wherein the needle arm ishollow; wherein the presser mechanism further includes a horizontal rockshaft journalled within the needle arm; a lifting connection operable intension only extending up from the presser bar and into the outer end ofthe needle arm to the rock shaft; and means whereby the rock shaft maybe actuated from the exterior of the machine frame.

NORMAN V. CHRISTENSEN.

